The AGW alarmist claim of "accelerating" global warming requires, at minimum, an increasing rate of temperature change as denoted by an increasing slope of a linear trend line. The two above charts plot the rolling 10-year trend (slope) of the annual GISS temperature data - the left axis of both charts represents slope in terms of temperature change per hundred years (century).

The leftmost chart reveals a large variation in speed and level of temperature change since the 1800s. The right chart takes the same data but only plots the last 15 years of GISS "acceleration" and "deceleration."

From the 2001 peak of a +3.48°C/century temperature rate, it has now fallen at the end of 2011 to an almost flat rate of +0.04°C/century temperature increase. Per the actual evidence, the increasing atmospheric levels of CO2 (grey arrow and grey area of charts) has zero influence on whether global temperatures are accelerating or decelerating.

These two charts do not represent predictions of future temperatures, but both clearly indicate that the IPCC and major climate research agencies have been substantially wrong in predicting "accelerating" warming.

Likewise, they have been substantially wrong in their assumption that the climate sensitivity to increasing levels of atmospheric CO2 is positive, growing and nearing a runaway tipping point. The empirical evidence proves all of these assertions to be essentially false.